The High Speed Packet Access (HSPA) technology is deployed in the WCDMA platform and is still evolving, including the High Speed Uplink Packet Access (HSUPA) on the uplink and High Speed Downlink Packet Access (HSDPA) on the downlink between a network side and a user equipment side of a communication network system. HSUPA technology is called Enhanced Uplink (EUL) by the third generation partnership project (3GPP). The main aim of EUL is to increase the uplink data transfer speed in the UMTS environment.
For EUL, there are two kinds of physical channels on the uplink: Enhanced Dedicated Physical Data CHannel (E-DPDCH) and Enhanced Dedicated Physical Control CHannel (E-DPCCH). There may be several E-DPDCH on each radio link. The E-DPCCH is a physical channel used to transmit control information associated with the transport channel Enhanced Dedicated CHannel (E-DCH) which is mapped onto E-DPDCH. There is at most one E-DPCCH on each radio link. The E-DPCCH and E-DPDCH are transmitted in parallel.
The Hybrid Automatic Repeat reQuest (HARQ) profile is carried over E-DPCCH. HARQ is a mechanism designed to provide error correction and packet retransmission across the radio interface.
The High Speed Dedicated Physical Control CHannel (HS-DPCCH) exists on the uplink in EUL for transferring control information such as the HARQ ACK/NACK and CQI information.
There are two transmission time interval (TTI) length settings for EUL, 10 ms and 2 ms. In each TTI, the available E-DCH power is calculated as in Formula (1) and further illustrated in FIG. 2.PE-DCH,available=PMAX,UE−PDPCCH−PE-DPCCH−PHS-DPCCH  (1)
Where PE-DCH,available 21 is the available E-DCH power, PMAX,UE is the maximum UE transmit power, PE-DPCCH 23 is the E-DPCCH transmit power during the first slot of an E-DCH TTI and PHS-DPCCH 22 is the HS-DPCCH transmit power. PDPCCH 24 is the DPCCH transmit power.
The available E-DCH power is an input for Enhanced Transport Format Combination (E-TFC) selection. In an EUL system, there are multiple factors that affects the E-TFC selection, e.g. the EUL grant, the maximum available E-DCH power, the available E-DCH data and UE capability etc. By looking up the predetermined E-TFC table and considering all of the factors mentioned above, UE selects a maximum usable E-TFC. FIG. 3 illustrates an example of the E-TFC selection. The power needed for an E-DCH transmission is calculated from two power offsets relative to DPCCH. One power offset is associated with each E-TFC and one power offset is associated with the hybrid-ARQ profile. The resulting transmit power is then calculated by adding these two power offsets to the DPCCH power. When the required transmit power for different E-TFC set has been calculated, the UE may calculate which E-TFC set is possible to use from a power perspective. The UE then selects the E-TFC by maximizing the amount of data that can be transmitted given the power constraint and the scheduling grant. Thus, 33 denotes the required E-TFCs that can carry all of the available EUL data for a certain UE, 32 the serving grant and 33 denotes the usable E-TFCs that are determined by the available power. Then UE chooses E-TFC 1 which can use up the available E-DCH power.
The timing of a HSDPA channel is shown in FIG. 4. The High-Speed Share Controlled CHannel (HS-SCCH) is used to send the controlling information to the UE, including Transport-Format and Resource-related Information (TFRI), Internal Information and Hybrid-ARQ-related information. The High-Speed Downlink Shared Channel (HS-DSCH) starts to transmit two slots after the HS-SCCH transmission. The UE knows whether it should receive the followed HS-DSCH with the information in the first HS-SCCH slot. The ACK/NACK (A/N) information is sent over the High-Speed Dedicated Physical Control CHannel (HS-DPCCH) after the received HS-DSCH has been processed. The processing delay denoted X in FIG. 4, from the end of HS-DSCH reception to the start of HS-DPCCH transmission is about 5 ms.
The HS-DPCCH is the control channel with 2 ms TTI for transmitting the HARQ and channel quality information, which is called Acknowledged/Not Acknowledged (ACK/NACK) and downlink Channel Quality Indicator (CQI) respectively. The CQI and the ACK/NACK over HS-DPCCH are used in MAC-hs scheduler in the downlink. FIG. 5 shows the HS-DPCCH frame structure: ACK/NACK in the first slot, CQI feedback in the next two slots. Since the CQI feedback may be configured to be transmitted in a fixed cycle and the ACK/NACK feedback is only transmitted after UE received an HS-DSCH, the CQI and ACK/NACK feedback may not always be transmitted simultaneously. That is, it may be possible that Slot 1 carries ACK/NACK but Slot 2 and Slot 3 are not used or Slot 1 is not used but Slot 2 and Slot 3 carry CQI.
Currently, when calculating the available E-DCH power, only the HS-DPCCH power consumption in the first slot during the EUL TTI is considered, while the possible HS-DPCCH power consumption during the rest of the slots is not considered, i.e. for 10 ms EUL TTI case, the possible HS-DPCCH power consumption within 2˜15th slot of the EUL TTI is not considered, and for 2 ms EUL TTI case, the possible HS-DPCCH power consumption within 2˜3rd slot of the EUL TTI is not considered. This may cause UE power limitation, which results in:                E-DCH quality is decreased;        The UE gains unnecessarily high grant due to the E-DCH quality decrease;        HS-DPCCH quality is decreased.        
FIGS. 6a and 6b illustrate an example that there is an ACK/NACK and/or CQI transmission when the UE is running EUL with the maximum transmit power for EUL 10 ms TTTI and 2 ms TTI respectively. In such cases, UE has to do scale the total transmit power to the maximum UE power according to predetermined strategy. Thus the E-DCH quality will be suffered.